Tsukuba University has partnered over the past few years with Athlete Intelligence to conduct medical research on the impact of head collisions within contact sports in Japan. This is a summary of the recently released (May 2017) research article published by Takashi Fukudah, Sekiya Koike, Syumpei Miyakawa and Yuki Yamamoto from Tsukuba University.
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The study outfitted 23 players who belonged to Tsukuba University Kantoh Collegiate American Football Association D2 with Athlete Intelligence’s Vector MouthGuard. The Vector MouthGuard was chosen because it’s equipped with 6 degrees of freedom that measures head linear acceleration, rotational acceleration, head injury criterion, impact location and the number of impacts. It has also been used in other similar studies in the U.S. and is respected for its proven accuracy.
Interest in the study emerged because while many similar studies have been conducted in the U.S. there are no such studies in Japan. The aim of the study “is to better understand head impacts during actual collisions between American football players from Japanese Universities,” as quoted in the article.
The study found that the number of collisions during practices in Japan was significantly higher than in the US. These impacts are much higher during games than practices and that lineman undergo more head collisions than those of backs.
The total number of head impacts that occurred during the study of one football season was 1,085 during games and 7,231 during practice sessions. Linemen received 644 of the impacts during games and backs received 441. While one player received 128 head impacts, another only received 11 for a median average for 40.5 impacts.
While Japan play shorter matches, 12-minute quarters versus 15-minute quarters in American football, the average number of collisions were similar between the two games. It indicated that the actual number of collisions is higher among Japanese players compared to those in the U.S.
Even though linemen undergo more collisions than backs, they experience hits with a lower g-force than backs. Since backs on both teams accelerate further distances it causes the collisions to be more intense. So, while the linemen received more hits, the harder hits were recorded by the backs.
The study determined that the different structure of practices between the Japanese team and other U.S. football teams could affect the increased head impacts in the Japanese players. “In particular, the number of collisions during practice sessions varies depending on the practice method, strategy and coaching of each university."”
Even though the study recorded 8,316 impacts none of them resulted in concussions. The study explains that while measurements of acceleration, deceleration and location are made possible by the sensors available for research, such as the Vector MouthGuard used in this study, there is still a lack of data for concussion diagnoses.
Currently all the data from these types of studies are not conclusive enough to estimate the concussion risk threshold. For all the complete data, with references to multiple other studies, the article can be downloaded from the Journal of Physical Fitness and Sports Medicine.